The present invention relates in general to particle moving and more particularly concerns novel techniques and apparatus for establishing laminar flow in tubes of small diameter so that small particles, such as cells, may be examined one-by-one and the passage of each by a counting point related to the passage at a radiation or other characteristic measuring point. A system according to the invention is especially suitable for automatically measuring radiation from each of a sequence of cells for detecting malignant cells generally in accordance with the techniques disclosed in U.S. Pat. Nos. 3,857,033 and 3,780,291.
The latter patent describes a system in which cells suspended in a fluid flow past one of a particle detector and radiation detector and then the other. While that system produced useful results, there were a number of inaccuracies. The source of these inaccuracies was not easily discovered. It was discovered that one source of error is turbulence developing in the flow channel making it difficult to associate the detection of a cell with the radiation from the detected cell.
Accordingly, it is an important object of the invention to provide improved methods and means for measuring characteristics of each of a plurality of particles.
It is another object of the invention to achieve the preceding object while overcoming one or more of the problems encountered in the prior art.
It is another object of the invention to achieve one or more of the preceding objects while inducing particle dispersion.
It is still another object of the invention to achieve one or more of the preceding objects with a stable flow rate while avoiding particle blockage.
It is yet another object of the invention to achieve one or more of the preceding objects while reducing contamination.
It is a further object of the invention to achieve one or more of the preceding objects while automatically detecting a sample containing malignant cells.